The present application relates to coextruded sheets adapted for use in form, fill and seal packaging operations and packages manufactured from such sheets.
Form, fill and seal (FFS) packaging is widely used to package a broad variety of products, including disposable medical devices, food stuffs and similar products. In one type of FFS packaging, materials corresponding to a lidstock for packages and a bottom or forming web are supplied in rolls. The forming web material is indexed from the roll into a heating zone where it is heated to forming temperatures. The heated forming web material is then either immediately formed or indexed into a forming station area where multiple box or cup shaped compartments are formed from the forming web using any one of a number of thermoforming techniques (i.e., drape forming, matched mold forming, vacuum forming or pressure bubble-plug assist vacuum forming). Other thermoforming methods are also known.
After forming, the bottom web is typically chilled or cooled and the product to be packaged is inserted into the individual formed compartments. The lidstock material is then applied to the forming web, sealing the compartments. The lidstock material may be sealed to the upper perimeter of the individual compartments using an adhesive and/or by heat sealing. These formed serially connected packages can then be cut from the web and trimmed to the desired final shape. Secondary functions that are selectively integrated into the process (i.e., printing or decorating) either before or after forming, may include embossing, notching, slotting, punching, labeling, counting and stacking.
Although these packages provide numerous advantages, the material incompatibility of the formed bottom web and lidstock can result in delamination, stringing, and/or peeling of the lidstock from the formed bottom web. In addition, many materials used in these packages are only suitable for use in limited applications and cannot withstand the wide range of temperatures, times, and pressures used during many sealing and sterilization processes. Thus, there exists a need for improved sheets useable as lidstock and forming webs in form, fill and seal applications.